Xanthodaphne pichi, Figueira, Raquel Medeiros Andrade & Absalão, Ricardo Silva, 2012

Figueira, Raquel Medeiros Andrade & Absalão, Ricardo Silva, 2012, Deep-water Raphitomidae (Mollusca, Gastropoda, Conoidea) from the Campos Basin, southeast Brazil, Zootaxa 3527, pp. 1-27 : 11-13

Xanthodaphne pichi n. sp.

( Figs. 16–19 )

Type material: Holotype MNRJ 30289 [1] OP II # 84 (22° 26' 28"S, 39° 58' 53"W), 3.88 mm, 1046m. Paratype IBUFRJ 17063 [1] OP I # 59 (21° 52' 59"S, 39° 55' 30"W), 6.98 mm, 750m. Paratype MZSP 108229 [1] OP I # 84 (22° 26' 27"S, 39° 58' 51"W), 4.64 mm, 1050 m. Paratype MCZ 374807 [1] OP I # 1 (22° 41'S, 40° 07'W - 22° 44'S, 40° 10'W), 15.72 mm, 1318 - 1305 m. Paratype MCZ 374808 [1] OP II # 78 (22° 37' 02"S, 39° 56' 20"W), 4.6 mm, 1945 m. Paratype MNHN [2] OP II # 53 (22° 04' 45"S, 39° 41' 58"W), 3.12 mm and 4.02 mm, 1910m. Paratype USNM 1187765 [1] OP I # 53 (22° 04' 46"S, 39° 43' 02"W), 4.02 mm, 1950m. Paratype USNM 1187766 [2] OP II # 58 (21° 57' 26"S, 39° 40' 34"W), 2.9 mm and 3.16 mm, 1942m.

Type locality: 22° 26' 28"S, 39° 58' 53"W, Campos Basin, Southeast Brazil, Southwestern Atlantic, 1046 m.

Material examined: Type material and 18518 [2] OP II # 49; 18519 [1] OP II # 52; 18520 [4] OP II # 53; 18521 [2] OP II # 58; 18522 [2] OP II # 62; 18523 [4] OP II # 77; 18524 [1] OP II # 78; 18526 [1] OP I # 51; 18527 [1] OP I # 53; 18528 [2] OP I # 57; 18529 [1] OP I # 58; 18530 [2] OP I # 62; 18531 [1] OP I # 72; 18532 [1] OP I # 84.

Description: Shell moderately plump, white, up to 15.72 mm long. Protoconch with about 3.5 whorls, yellowish. Protoconch 1 with rows of tiny crosses, resembling barbed wire. Protoconch 2 with diagonal cancellation on the lower 2/3 of the whorls, and with axial riblets crossed by fine spiral threads on the upper 1/3 at the first whorl. The other whorls of protoconch 2 do not show fine spiral threads on the upper 1/3, but rather microscopic threads in the interspaces between the axial riblets. Clear-cut proto-teleoconch boundary. Teleoconch whorls evenly rounded. Subsutural rounded spiral band present. Subsutural zone with slightly curved thin axial riblets. Remainder of the shell macroscopically smooth, except for very faint sinoidal scars that vanish towards the fasciole. Microscopic grains over entire teleoconch surface. Suture shallow. Base moderately long. Fasciolar region with about 5 oblique and very faint cords. Anal sinus shallow and wide. Inner lip very thin, reflected over parietal wall. Outer lip thin. Anterior siphonal canal broad and moderately short. Aperture elliptical.

Etymology: Pichí is a word in Tupy, a major language of Brazilian indigenous peoples, and means “smooth”, referring to the smooth shell surface typical of this species.

Geographic distribution: Only known from Campos Basin, off Rio de Janeiro, 722–1950 m.

Discussion: The species has a subsutural zone clearly showing thin curved axial riblets, as the other species of the genus Xanthodaphne . On the other hand, this species does not have spiral sculpture, which makes this generic positioning uncertain. Besides the absence of spiral sculpture, Xanthodaphne pichi can be distinguished from the other species of the genus by the absence of an evident shoulder. In this genus, X. pachia ( Watson, 1886: 353, pl. 19, fig. 5) is the most similar to Xanthodaphne pichi , but can be distinguished by its plumper profile and shorter axial riblets below the suture. This species is very similar to Xanthodaphne pyriformis Schepman (1913: 83[447], pl. 30, fig. 7) reported from Indonesia, but Xanthodaphne pichi seems to have more convex whorls.

Figures

FIGURES 12 – 19. 12, 13 — Xanthodaphne dalmasi Dautzenberg & Fischer, 1896, IBUFRJ 18498; 12 — 4.94 mm, whole shell; 13 — protoconch; 14, 15 — Xanthodaphne araneosa Watson, 1881, IBUFRJ 18537; 14 — 5.18 mm, whole shell; 15 — protoconch; 16, 17, 18, 19 — Xanthodaphne pichi n. sp.; 16, 18, 19 — Holotype MNRJ 30289; 16 — 3.88 mm, whole shell; 18 — detail of shell surface; 19 — protoconch; 17 — Paratype IBUFRJ 17063, 6.98 mm, whole shell. Scale bars: 12, 15 and 16 = 500 μm; 13 and 19 = 300 μm; 14 and 16 = 1 mm; 18 = 50 μm.